From: Theo Buehler <tb@theobuehler.org>
Subject: Re: bgpd: fix mrt matching for peer groups
To: tech@openbsd.org
Date: Mon, 2 Mar 2026 09:44:52 +0100

On Tue, Feb 17, 2026 at 05:43:07PM +0100, Claudio Jeker wrote:
> Noticed the hard way. If you set a dump directive on a peer inside a group
> that peer directive is wrongly applied to all peers and not only the
> single peer.
> 
> This comes from the fact that the group_id is set even for peer dumps and
> this confuses the code in session.c::session_mrt_dump_state() etc.
> Fixing this is simple, set group_id only for group matches.
> 
> This caused another issue in printconf.c since there the logic is also not
> quite right. I tried to use a similar check in print_mrt() as is done in
> session.c and added some comment since it is not so obvious. 
> 
> The diff below should fix those issues.

ok tb

> -- 
> :wq Claudio
> 
> Index: parse.y
> ===================================================================
> RCS file: /cvs/src/usr.sbin/bgpd/parse.y,v
> diff -u -p -r1.487 parse.y
> --- parse.y	6 Dec 2025 09:48:30 -0000	1.487
> +++ parse.y	17 Feb 2026 14:16:18 -0000
> @@ -4768,7 +4768,7 @@ add_mrtconfig(enum mrt_type type, char *
>  			n->group_id = p->conf.id;
>  		} else {
>  			n->peer_id = p->conf.id;
> -			n->group_id = p->conf.groupid;
> +			n->group_id = 0;
>  		}
>  	}
>  	if (rib) {
> Index: printconf.c
> ===================================================================
> RCS file: /cvs/src/usr.sbin/bgpd/printconf.c,v
> diff -u -p -r1.184 printconf.c
> --- printconf.c	4 Feb 2026 13:49:23 -0000	1.184
> +++ printconf.c	17 Feb 2026 15:30:58 -0000
> @@ -1193,9 +1193,15 @@ print_mrt(struct bgpd_config *conf, uint
>  	if (conf->mrt == NULL)
>  		return;
>  
> +	/*
> +	 * If pid == 0 then this needs to match for the any config rule
> +	 * and in that case gid == 0 as well. If pid != 0 then either
> +	 * match against peer_id or group_id depending which one is set.
> +	 */
>  	LIST_FOREACH(m, conf->mrt, entry)
> -		if ((gid != 0 && m->group_id == gid) ||
> -		    (m->peer_id == pid && m->group_id == gid)) {
> +		if ((pid == 0 && m->peer_id == 0 && m->group_id == 0) ||
> +		    (m->peer_id != 0 && m->peer_id == pid) ||
> +		    (m->group_id != 0 && m->group_id == gid)) {
>  			printf("%s%sdump ", prep, prep2);
>  			if (m->rib[0])
>  				printf("rib %s ", m->rib);
>